Identification of wheat-Thinopyrum intermedium alien disomic addition lines conferring resistance to stripe rust

Lin, F., Sun, Q., Xu, S. C., Chen, X. M., Zhang, L. J., Zhang, C. Y., Xu, Y. F., Miao, Q., Qu, B., Li, N. and Zhai Q. 2009. Identification of wheat-Thinopyrum intermedium alien disomic addition lines conferring resistance to stripe rust. Can. J. Plant Sci. 89: 569-574. Thinopyrum intermedium carries many useful traits for wheat genetic improvement. To identify genes conferring resistance to stripe rust caused by Puccinia stiiformis f. sp. tritici in Zhong4, one of the Zhong series of partial amphiploids from the hybrids of common wheat x Th. intermedium, a cross was made between Zhong4 and a Chinese Spring ph1b mutant (CS-ph1b). The parents, F-1, F-2 plants and F-5 lines of the cross were tested with Chinese predominant race CYR31 of P. striiformis f. sp. tritici in the seedling stage under controlled greenhouse conditions. Of 201 F, seedlings tested with race CYR31, 149 were resistant and 52 were susceptible. The segregation Fit a 3 resistant: 1 susceptible ratio, indicating that a single dominant gene conferred resistance to the race CYR31. This result was further confirmed by the segregation of F5 lines into 1: 1 ratio (P =0.77). Using the Schiff dyeing method, the chromosome number in the root-tip cells of 10 F5 resistant lines (total 42 plants) was determined. Two alien addition lines (5-1-2-1-1-5, 5-1-2-1-1-6) with the smallest chromosome number (2n =42 + II) were identified. A total of 105 pollen mother cells were examined at metaphase 1 (PMCs M 1) for meiotic chromosome pairing. The lines 5-1-2-1-1-5 and 5-1-2-1-1-6 showed regular meiosis, exhibiting 22 ring or rod bivalents (2n = 22 II). The GISH results indicated that lines 5-1-2-1-1-5 and 5-1-2-1-1-6 were wheat-Th. intermedium alien disomic addition lines with 21 pairs of wheat chromosomes and one pair of Th. intermedium chromosomes. These two lines were all resistant to stripe rust, suggesting that they can be used as donors of stripe rust resistance genes and have great potential to play important roles in wheat stripe rust resistance breeding programs in China and the world.